CVE-2026-80789

nvmet-tcp: bound SGL data length before allocating command buffers

Published Sep 4, 2026 CVSS n/a EPSS < 1% KEV · Not listed

Description

In the Linux kernel, the following vulnerability has been resolved:

nvmet-tcp: bound SGL data length before allocating command buffers

nvmet_tcp_map_data() reads the host-controlled 32-bit sgl->length
and, for the in-capsule offset descriptor (type 0x01), checks it
against port->inline_data_size before use. Any other SGL descriptor
type -- including the non-inline transport SGL data-block descriptor
(type (NVME_TRANSPORT_SGL_DATA_DESC << 4) | NVME_SGL_FMT_TRANSPORT_A,
the type a real host uses for out-of-capsule writes) skips that check
entirely and falls straight through to:

cmd->req.sg = sgl_alloc(len, GFP_KERNEL, &cmd->req.sg_cnt);

with len taken directly from the wire, unbounded up to 4 GiB.

nvmet_req_init() only parses the command and never inspects
sgl->length, and nvmet_check_transfer_len() -- the only other place
transfer_len is validated -- runs later, from req->execute(), after
the allocation has already happened. For a write command the target
responds with an R2T and parks the command waiting for the host to
send the data; if the host (or an unauthenticated peer that simply
never follows up) never does, the sgl_alloc() buffer stays resident
for the life of the command. NVMe/TCP has no mandatory authentication
in the default configuration, so any peer able to reach the target
portal and complete a Fabrics connect can drive this with a single
crafted command, repeatable across queues and connections for
amplification. This is unbounded kernel memory allocation
triggered by a remote, effectively unauthenticated peer.

Validate len against the same NVMET_TCP_MAXH2CDATA ceiling this file
already uses to bound per-PDU H2C data, for every SGL descriptor type,
before doing any allocation. This closes the gap for the non-inline
descriptor while leaving the existing, tighter inline_data_size check
in place for the in-capsule case.

Runtime-verified on a v6.19 KASAN stand: with this bound in place, a
crafted write command carrying an oversized non-inline SGL length is
rejected before sgl_alloc() runs, where the same request previously
drove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that
stayed resident pending an R2T the host never satisfies.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< f63e89a0310264264923f84406dea05fe752de62
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< 0952541b153e258b99d39cdb03ea6919fdeb41d0
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< 25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< d2acc96c528d589f5827cfb90e8e9229dd9d8cb4
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< 6d27199ebe8cb223022150f74be13f154a964474
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< 14dbe37681a6a7e346fc147bb363ec7cca3180a0
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< d895e66628f939edbb98608f6e033d3d39e6e546
`872d26a391da92ed8f0c0f5cb5fef428067b7f30`	affected	< 4a3f00262a044e8e15064b1a6860968bf0500bf4

Linux

affected

Version	Status	Constraints
`5.0`	affected	—
`0`	unaffected	< 5.0
`5.10.269`	unaffected	≤ 5.10.*
`5.15.220`	unaffected	≤ 5.15.*
`6.1.187`	unaffected	≤ 6.1.*
`6.6.156`	unaffected	≤ 6.6.*
`6.12.106`	unaffected	≤ 6.12.*
`6.18.47`	unaffected	≤ 6.18.*
`7.1.11`	unaffected	≤ 7.1.*
`7.2.1`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Versions

Linux

Linux Kernel

Version	Status	Scheme	Platform
`[872d26a391da92ed8f0c0f5cb5fef428067b7f30,f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5)`	affected	code_commit	—
`[872d26a391da92ed8f0c0f5cb5fef428067b7f30,f63e89a0310264264923f84406dea05fe752de62)`	affected	code_commit	—
`[872d26a391da92ed8f0c0f5cb5fef428067b7f30,0952541b153e258b99d39cdb03ea6919fdeb41d0)`	affected	code_commit	—
`[872d26a391da92ed8f0c0f5cb5fef428067b7f30,25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22)`	affected	code_commit	—
`[872d26a391da92ed8f0c0f5cb5fef428067b7f30,d2acc96c528d589f5827cfb90e8e9229dd9d8cb4)`	affected	code_commit	—
`[872d26a391da92ed8f0c0f5cb5fef428067b7f30,6d27199ebe8cb223022150f74be13f154a964474)`	affected	code_commit	—
`[872d26a391da92ed8f0c0f5cb5fef428067b7f30,14dbe37681a6a7e346fc147bb363ec7cca3180a0)`	affected	code_commit	—
`[872d26a391da92ed8f0c0f5cb5fef428067b7f30,d895e66628f939edbb98608f6e033d3d39e6e546)`	affected	code_commit	—
`[872d26a391da92ed8f0c0f7cb5fef428067b7f30,4a3f00262a044e8e15064b1a6860968bf0500bf4)`	affected	code_commit	—

Linux

Linux Kernel

Version	Status	Scheme	Platform
`5.0`	affected	generic	—
`[0,5.0)`	unaffected	generic	—
`[5.10.269,5.10.*]`	unaffected	generic	—
`[5.15.220,5.15.*]`	unaffected	generic	—
`[6.1.187,6.1.*]`	unaffected	generic	—
`[6.6.156,6.6.*]`	unaffected	generic	—
`[6.12.106,6.12.*]`	unaffected	generic	—
`[6.18.47,6.18.*]`	unaffected	generic	—
`[7.1.11,7.1.*]`	unaffected	generic	—
`[7.2.1,7.2.*]`	unaffected	generic	—
`[7.3-rc1,*]`	unaffected	generic	—

Remediation

No solution or workaround provided in the CVE record

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4777-1	linux security update
Debian DLA	DLA-4788-1	linux-6.12 security update
Ubuntu USN	USN-8961-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9019-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9020-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9022-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9023-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9024-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9025-1	Linux kernel vulnerabilities
Ubuntu USN	USN-9026-1	Linux kernel (Azure) vulnerabilities
Ubuntu USN	USN-9029-1	Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN	USN-9039-1	Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN	USN-9040-1	Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN	USN-9066-1	Linux kernel (HWE) vulnerabilities
Ubuntu USN	USN-9091-1	Linux kernel (NVIDIA Tegra) vulnerabilities

Metrics

No CVSS v4.0

No CVSS v3.1

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.234% probability within 30 days)

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/stable/c/0952541b153e258b99d39cdb03ea6919fdeb41d0
https://git.kernel.org/stable/c/14dbe37681a6a7e346fc147bb363ec7cca3180a0
https://git.kernel.org/stable/c/25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22
https://git.kernel.org/stable/c/4a3f00262a044e8e15064b1a6860968bf0500bf4
https://git.kernel.org/stable/c/6d27199ebe8cb223022150f74be13f154a964474
https://git.kernel.org/stable/c/d2acc96c528d589f5827cfb90e8e9229dd9d8cb4
https://git.kernel.org/stable/c/d895e66628f939edbb98608f6e033d3d39e6e546
https://git.kernel.org/stable/c/f63e89a0310264264923f84406dea05fe752de62
https://git.kernel.org/stable/c/f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5

History

Sep 4, 2026 9:45 PM Weaknesses updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-789

Sep 4, 2026 3:30 PM Description updated. Title updated. First appearance in the feed. Affected versions updated. Affected vendors updated. Added references View changes

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: bound SGL data length before allocating command buffers nvmet_tcp_map_data() reads the host-controlled 32-bit sgl->length and, for the in-capsule offset descriptor (type 0x01), checks it against port->inline_data_size before use. Any other SGL descriptor type -- including the non-inline transport SGL data-block descriptor (type (NVME_TRANSPORT_SGL_DATA_DESC << 4) \| NVME_SGL_FMT_TRANSPORT_A, the type a real host uses for out-of-capsule writes) skips that check entirely and falls straight through to: cmd->req.sg = sgl_alloc(len, GFP_KERNEL, &cmd->req.sg_cnt); with len taken directly from the wire, unbounded up to 4 GiB. nvmet_req_init() only parses the command and never inspects sgl->length, and nvmet_check_transfer_len() -- the only other place transfer_len is validated -- runs later, from req->execute(), after the allocation has already happened. For a write command the target responds with an R2T and parks the command waiting for the host to send the data; if the host (or an unauthenticated peer that simply never follows up) never does, the sgl_alloc() buffer stays resident for the life of the command. NVMe/TCP has no mandatory authentication in the default configuration, so any peer able to reach the target portal and complete a Fabrics connect can drive this with a single crafted command, repeatable across queues and connections for amplification. This is unbounded kernel memory allocation triggered by a remote, effectively unauthenticated peer. Validate len against the same NVMET_TCP_MAXH2CDATA ceiling this file already uses to bound per-PDU H2C data, for every SGL descriptor type, before doing any allocation. This closes the gap for the non-inline descriptor while leaving the existing, tighter inline_data_size check in place for the in-capsule case. Runtime-verified on a v6.19 KASAN stand: with this bound in place, a crafted write command carrying an oversized non-inline SGL length is rejected before sgl_alloc() runs, where the same request previously drove an unbounded ~256 MiB kernel allocation (up to 4 GiB) that stayed resident pending an R2T the host never satisfies.
Title		nvmet-tcp: bound SGL data length before allocating command buffers
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/0952541b153e258b99d39cdb03ea6919fdeb41d0 https://git.kernel.org/stable/c/14dbe37681a6a7e346fc147bb363ec7cca3180a0 https://git.kernel.org/stable/c/25ad03d5c0e858c4b63f1e4b6d461d2af1b30b22 https://git.kernel.org/stable/c/4a3f00262a044e8e15064b1a6860968bf0500bf4 https://git.kernel.org/stable/c/6d27199ebe8cb223022150f74be13f154a964474 https://git.kernel.org/stable/c/d2acc96c528d589f5827cfb90e8e9229dd9d8cb4 https://git.kernel.org/stable/c/d895e66628f939edbb98608f6e033d3d39e6e546 https://git.kernel.org/stable/c/f63e89a0310264264923f84406dea05fe752de62 https://git.kernel.org/stable/c/f6e51b09cbaa5f6f6e6a3a9dafa666f76c37aab5